Ruby 2.7: Add Complex#<=>

CHANGELOG.md

@@ -17,6 +17,7 @@ Compatibility:
 * Implement `Enumerable#tally` and `Enumerable#filter_map` (#2144 and #2152, @LillianZ).
 * Implement `Range#minmax`.
 * Pass more `Enumerator::Lazy#uniq` and `Enumerator::Lazy#chunk` specs (#2146, @LillianZ).
+* Implement `Complex#<=>` (#2004, @ssnickolay).
 
 Performance:
 

src/main/ruby/truffleruby/core/complex.rb

@@ -36,7 +36,7 @@
 
 class Complex < Numeric
 
-  undef_method :%, :<, :<=, :<=>, :>, :>=, :between?, :clamp, # comparable
+  undef_method :%, :<, :<=, :>, :>=, :between?, :clamp, # comparable
                :div, :divmod, :floor, :ceil, :modulo, :remainder,
                :round, :step, :truncate, :i, :negative?, :positive?
 
@@ -373,6 +373,16 @@ def marshal_load(ary)
     self
   end
 
+  def <=>(other)
+    if imag == 0 && other.kind_of?(Numeric)
+      if other.kind_of?(Complex) && other.imag == 0
+        real <=> other.real
+      elsif other.real?
+        real <=> other
+      end
+    end
+  end
+
   I = Complex(0, 1)
 
 end

test/mri/excludes/Complex_Test.rb

@@ -16,4 +16,3 @@
 exclude :test_rationalize, "needs investigation"
 exclude :test_Complex_with_invalid_exception, "needs investigation"
 exclude :test_conv, "needs investigation"
-exclude :test_cmp, "needs investigation"